1. Field of the Invention
This invention relates to an insert material for solid phase diffusion welding for nickel (Ni) base superalloy and method therefor, particlularly to an insert material for solid phase diffuion welding for Ni base superalloy and method therefor suited for attaining high welding strength.
Insert material for nickel base superalloy solid phase diffusion welding and method therefor relating to the present invention can be preferably used in, for instance, stator blades, rotor blades of a gas turbine or a jet engine etc., or parts of a turbocharger and the like and other members requiring high strength at a high temperature and used for manuracture thereof.
2. Description of the Prior Art
In the prior arts related to the welding of superalloy are there liquid phase diffusion welding methods utilizing Ni-B system insert material or sputtered film, which for example are disclosed in Japanese Patent Publication No. Sho 49-6470 and Japanese Patent Laid-open No. Sho 47-33850. These methods are characterized in that the welding pressure is small.
However, said prior art is not considered with respect to the welding strength. The chemical composition of insert material for welding .gamma.'-precipitated-hardened Ni-base superalloy excellent in heat resisting strength is limited to that of Ni-B system ones or the like having the melting point lower than that of base metal, i.e. Ni base superalloy since the welding surface needs to be melted. As a result, the chemical composition of welding portion differs largely from that of base metal so that the reduction of strength of welding portion is a matter of concern. Also, the welding of oxide dispersion strengthened superalloy presents problems of cohesion of dispersed particles due to the melting of welding portion, so that the welding strength is considered to be reduced.
On the other hand, the reduction of welding strength is prevented by means of solid phase diffusion welding with the insert material having not only the strength equal to that of base metal, but also the composition suited for welding process.